Cylindrical banding jets



Nov. 22, 1966 e. A. WATSON 3,286,307

CYLINDRIGAL BANDING JETS Filed Sept. 9, 1965 4 Sheets-Sheet 1 Nov. 22, 1966 G. A. WATSON 3,286,307

CYLINDRICAL BANDING JETS Filed Sept. 9, 1963 4 Sheets-Sheet 2 Nov. 22, 1966 e. A. WATSON I CYLINDRICALBANDING JETS 4 Sheets-Sheet 3 Filed Sept. 9, 19 5 Nov. 22, 1966 G. A. WATSON CYLINDRICAL SANDING ms 4 Sheets-Sheet 4 Filed Sept. 9, 1963 GEORGE (UH United States Patent Ofitice 3,286,307 Patented Nov. 22, 1966 3,286,307 CYLINDRICAL BANDING JETS George A. Watson, Charlotte, N.C., assignor to Celanese Corporation of America, New York, N.Y., a corporation of Delaware Filed Sept. 9, 1963, Ser. No. 307,389 21 Claims. (Cl. 19-66) This invention relates to processes of and means for treating continuous filament tow.

Continuous filament tow, in which the number of filaments may range from several hundred to as high as 1,000,000 can be employed in the manufacture of a great variety of textile and non-textile products such as cigarette filters, clothing and furniture fabrics, pillow and upholstery battings, gas and liquid filters, sanitary napkin covers, and many others. Upon extrusion of the filaments and the collection thereof into bundles of appropriate size, the resultant tow is generally rendered coherent, i.e. the filaments are prevented from separating, by being crimped to the extent of about 4 to 20 -or more crimps per inch. The crimped tow is then baled or packed preparatory to being stored for further use or shipment.

When it is desired to employ such tow in the manufacture of any of the types of products referred to, it 15 necessary first to open the tow and to deregister the crimps thereof and then to transform the tow into a relatively wide band or web of filaments. It is the usual practice in opening crimped tow to pass the same, as it is extracted from the bale, through a type of preliminary spreading device known in the art by the name banding jet which flattens the tow into the form of a relatively narrow band or web of uniform width capable of being fed into the tow opening apparatus where the crimps are to be deregistered. Upon leaving the tow opening apparatus, the two is fed through another banding jet in which it is spread to the ultimate desired width preparatory to further treatment. These banding jets are generally in the form of a pair of spaced parallel plates between which is defined a flat, rectilinear passageway through which the tow is drawn, with one or both of the plates being provided with a number of elongated slots or other apertures through which air under pressure is admitted into the passageway. The air flowing into and through the passage thus serves to spread the tow into the relatively narrow flat band desired.

It is an object of the present invention to provide novel processes of spreadingtow into a flat band formation suitable for being subjected to a variety of tow treating operations.

It is also an object of the present invention to provide v novel banding jets for spreading crimped tow.

Another object of the present invention is the provision of processes of and means for spreading tow which entail movingthe tow through an arcuate passageway while a compressible fluid under'pressure is admitted into the said passage.

A more specific object of the present invention is the provision of handing jets in which the arcuate passageway for the tow is defined between a generally tubular member and an arcuate shield positioned adjacent and at least partly about the said member.

A further object of the present invention is the provision of such banding jets in which the fluid-admitting slots are provided in either the tubular member or the shield or in both and may be arranged to admit the pressurized fluid into the passageway either radially or nonradially with respect to the curvature of the path of movement of the tow.

The foregoing and other objects of the present invention, as well as the characteristics and advantages of preferred aspects of the processes and means conforming thereto, will be more clearly understood from the following detailed description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of a tow spreading apparatus employing a banding jet constructed in accordance with the principles of the present invention;

FIG. 2 is an exploded isometric view of the banding jet shown in FIG. 1 and illustrates the tubular member thereof as being provided with longitudinally extending radial slots;

FIG. 3 is a sectional view taken along the line 33 in FIG. 2;

FIG. 4 is a sectional view taken along the line 4-4 in FIG. 2;

FIG. 5 is a transverse sectional view of a slightly modified type of banding jet in which the fluid-admitting slots in the tubular member are non-radially oriented;

FIG. 6 is an isometric view of a tubular banding jet member provided with slots oriented codirectionally obliquely relative to the axis of the member;

FIG. 7 is a similar view of a tubular banding jet member having slots arranged bidirectionally obliquely relative to the axis of the member;

FIGS. 8 and 9 are diagrammatic end views of the banding jet illustrating the provision of passageways of varying thickness between the tubular and shield members; and

FIGS. 10 through 13 are transverse sectional views, similar to FIG. 5, of still further modified types of banding jets according to the present invention.

Generally speaking, the banding jet comprises a pair of complementarily a'rcuately surfaced members positioned adjacent each other with one of them having the con figuration of a concavely surfaced shield and extending partly about the other so as to define therebetween shallow arcuate passageway through which the tow or strand of filaments may be moved. In accordance with one aspect of the present invention, the convexly surfaced member is hollow, and its interior is in communication with a source of compressible fluid, e.g., air, under pressure. That part of this member which presents the convex boundary surface of the passageway is preferably made of metal or metal alloy or other material having a high resistance to the frictional wear of the passing filaments. The shield may be made of the same material, and if desired may be made of a suitable transparent plastic material to permit an inspection of the jets tow spreading action. The height of the passageway, i.e., the perpendicular distance between the mated surfaces of these members generally ranges between about and A1 inch.

More specifically, the convex boundary surface of the passageway is preferably consistuted by the outer surface of a right circular cylinder, while the concave boundary surface of the passageway is constituted by the inner surface of a curved plate having the configuration of an approximately 10 to 180, preferably between about and segment of a right circular cylinder. The arrangement of the two members may be such that the height of the passageway remains uniform from the tow inlet to the tow outlet, but it is contemplated, in accordance with the present invention, that the height of the passageway need not be uniform, i.e., that the height could vary from tow inlet to tow outlet. It will be understood, of course, that either a constant-height or a variable-height passageway may be defined between two non-cylindrical members, the only requirement being that the height of the passageway widthwise thereof, i.e., along any given generatrix of the convex boundary surface, must be uniform. The desired dimensioning of the passageway can be achieved by employing concave and convex surfaces of different curvatures, but it is preferred to utilize surfaces of like curvature sparated from each otherby means of suitably dimensioned spacers interposed between the two members at the opposite sides of the passageway.

Within the confines of the so-formed filament passageway, the convexly surfaced member is provided with a plurality of narrow slots through which the pressurized air is admitted into the passageway. Preferably, the air is under a pressure of about 2 psi. The air-admitting slots are oriented generally crosswise to the direction of movement of the tow through the passageway. The slots, if oriented with their longitudinal dimension extending obliquely to the direction of movement of the tow, may all be arranged codirectionally parallel, or they may be arranged in two groups of substantially parallel slots, with the slots of each group oriented transversely to the slots in the other, to define a herringbone pattern. The slots may extend through the convex surface either radially or chordally thereof. In the latter case, of course, the slots may be directed either in the direction of the tow inlet or in the direction of the tow outlet of the passageway. The purpose and advantages of such arrangements will be more fully set forth hereinafter. Preferably, the width of each slot ranges from about 0.004 inch to about 0.020 inch.

If desired, each of the openings in the convexly surfaced member, in lieu of being in the form of a relatively long and continuous slot, could be made up of a number of relatively short and discrete holes or apertures closely aligned to produce an effect substantially similar to that of a long slot. Also, in accordance 'with other aspects of the present invention, the air-admitting openings of whatever character may be provided in the shield member rather than in the convexly surfaced member, or alternatively respective sets of air-admitting openings each in communication with its associated plenum chamber may be provided in both of the passageway-defining members. In such a case, it is advantageous to position the openings in each of these members somewhat offset relative to the openings in the other member.

The processes according to the present invention are particularly well suited for use in, but are not limited to, the spreading of multifilament tow into fiat bands both prior and subsequent to a tow opening operation associated with the production of cigarette filters and nonwoven textile and non-textile products. Thus, the principles of the invention are applicable to the spreading of strands of filaments, e.g., tow or yarns, in connection with such operations as plasticizer, lubricant or other finish application or the like. Moreover, due to the possibility of so constructing the jets according to this invention as to enable the air admitted into the passageway to exert a positive feeding force on the passing filamentary material, the invention is applicable to the transporting of lightweight fabrics or like sheet materials having little dimensional stability and likely to be distorted or damaged by conventional feed rolls, e.g., 'marquisette and tricot fabrics, thin gage plastics or paper, etc.

The present invention is further particularly well suited for treatments as aforesaid of filamentary material composed of organic derivatives of cellulose such as the esters or ethers thereof. Thus, the filamentary material may comprise cellulose organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose benzoate, cellulose acetate formate, cellulose acetate propionate, cellulose acetate butyrate, and the like, ethers such as ethyl cellulose, etc. The esters may be ripened and acetone-soluble, such as conventional cellulose acetate, or may be substantially fully esterified, i.e., contain fewer than 0.29 free hydroxyl groups per anhydroglucose unit, such as cellulose triacetate.

The filaments may, of course, be made of other materials of thermoplastic nature. Examples of these materials are the superpolyamides such as nylon, superpolyesters such as polyethylene terephthalate, polyglycolic acid and copolymers thereof, polymers and copolymers of vinylidene compounds such as ethylene, propylene, vinyl chloride, vinylidene chloride, vinylidene cyanide, acrylonitrile, vinyl acetate, and the like.

Referring now more particularly to the drawings, the present invention will now be described as embodied in a tow spreading apparatus, but it should be remembered that such apparatus may, as hereinbefore indicated, serve other purposes. Hoving reference first to FIGS. 1 to 4, an apparatus 10 according to one aspect of the present invention for spreading crimped or otherwise coherent tow T extracted from a bale or other container C into the form of a fiat band B comprises a banding jet 11 constituted by an elongated convexly surfaced member 12 and an arcuate concavely surfaced shield 13 the length of which is coextensive with that of the member 12. In the illustrated embodiment of the invention, the member 12 is in a right circular cylinder, and the shield 13 is a curved plate which may be considered essentially a segment of such a cylinder. The cylinder 12 is hollow, and its opposite ends are closed air-tight by end walls 14 in .one of which is provided an opening 15. Suitable means (not shown), e.g., a bracket arm arrangement connected to one of the end walls 14, may be provided for rigidly securing the cylinder to any available supporting surface.

The shield 13 is seated on the cylinder 12 with the aid of a pair of arcuate spacer members 16 which engage the cylinder at the ends thereof. Bolts, screws or other fasteners 17 or such means as magnets, springs, etc. may be employed to secure the shield ,to the cylinder. By virtue of this arrangement there is defined between the inner concave surface of the shield 13 and the outer convex surface of the cylinder 12 an arcuate passageway extending partly along the circumference of the cylinder, the height or thickness of which passageway depends on the dimensions of the spacer members 16. In the embodiment of the invention illustrated in FIGS. 1 to 4, these spacer members are of uniform radial thickness. It will be clear, therefore, that the height of the passageway, i.e., the radial or perpendicular distance from the surface of the cylinder to the adjacent surface of the shield, is uniform from the inlet at which the tow T enters the passageway to the outlet at which the tow leaves the passageway in the form of the flat band B.

It will likewise be understood that the spacer members 16 may be constructed in the form of arcuate wedges 38, increasing gradually in thickness from one end to the other as depicted in FIGURE 12. If the shield 13 is positioned atop such spacers, its edge at the inlet end of the passageway will be either closer to or farther away from the surface of the cylinder than the edge at the outlet end, depending on the orientation of the spacer wedges, thereby providing a passageway the height of which varies from inlet to outlet. This is diagrammatically illustrated in FIGS. 8 and 9, from which it can be seen that if the thinner ends of the spacer wedges face toward the source of the tow (FIG. 8), the inlet dimension a of the passageway is smaller than the outlet dimension b, while if the thinner ends of the spacer wedges face away from the source of the tow (FIG. 9), the inlet dimension a of the passageway is greater than the outlet dimension b. v The purpose and function of such an arrangement will be more fully explained presently.

As clearly shown in FIGS. 2 and 4, the cylinder 12, in a segmental region of the wall thereof corresponding essentially to the arc of the shield 13, is provided with a plurality of openings in the form ofnarrow elongated slots 18 which, in this embodiment of the invention, are parallel to one another and oriented perpendicularly to the direction of movement of the tow T through the passageway. In lieu of slots, the openings 18 may, as hereinbefore set forth, be constituted by respective sets of small circular openings ,or apertures in substantially diametral alignment With each other. The openings 18 establish communication between the interior of the cylinder 12 and the tow passageway.

Pressurized air or similar fluid is fed into the interior of the cylinder 12 from a source 19 thereof, e.g., a compressor or the like, via a duct or hose 20 which is connected to the cylinder end wall opening 15 and controlled by a regulating valve 21. The cylinder interior thus constitutes a plenum chamber from which the air is admitted into the passageway via the openings 18.

In operation, the tow is generally pulled through the banding jet 11 by positively driven rolls (not shown). Depending on the treating operation to which the spread tow is to be subjected thereafter and on the denier per filament of the strand, the tension on the filaments should be not greater than about to about 1000 milligrams per fil. While the tow is moving through the passageway, the pressurized air reaching the plenum chamber constituted by the hollow interior of the cylinder 12 expands in the latter and then enters the filament passageway over substantially the entire expanse thereof. Due to the uniform dimensions of the passageway, this air will diffuse in both directions from each slot or opening, i.e., both codirectionally with and countercurrent to the moving tow, toward the inlet as well as toward the outlet of the passageway. This action, which is effectively superimposed on the relatively turbulent air flow conditions existing at the locations of the various slots or openings, ensures that the filamentary tow is spread into the form of a flat band or ribbon having substantially the same width as the passageway.

The openings 18 in the cylinder 12 will generally be formed radially of the cylinder, so that the pressurized air enters the passageway radially and tends to be distributed substantially equally both in and opposite to the direction of movement of the tow through the passageway. For purposes of either retarding or accelerating the tow movement, it may at times be desired, however, that air entering the passageway should flow either preferentially in the direction of movement of the tow or preferentially opposite to the direction of movement of the tow. In the banding jet of FIGS. 1 to 4, this goal may be achieved by concentrating the openings either adjacent the outlet end or adjacent the inlet end of the passageway. Thus, if the openings are located principally in the first one third of the passageway, it is found that a retarding action on the tow movement (with a consequent increase in tension) is effected. Conversely, when the openings are located principally in the last one third of the passageway, an accelerating action on the tow movement (with a consequent decrease in tow tension) is effected.

Similar results may be achieved by employing a slightly modified banding jet construction of the type illustrated in FIG. 5. In a banding jet of this type, the openings 18a in the cylinder 120 are formed non-radially, i.e., chordally, of the cylinder. Accordingly, air admitted into the passageway defined between the cylinder 12a and its associated shield 13 will tend to flow primarily in a clockwise direction relative to the cylinder (as viewed in FIG. 5). Thus, this airflow will be in the direction of movement of the tow if the latter is being fed through the passageway in the direction of the arrow X, and opposite to the direction of the movement of the tow if the latter is being fed through the passageway in the direction of the arrow Y. In the first case, therefore, the airflow will have a tendency to accelerate the movement of the tow through the passageway, thereby decreasing the tension on the filaments of the tow. In the second case, the airflow will have a tendency to retard or brake the movement of the tow, thereby increasing the tension on the filaments of the tow.

Referring again to FIGS. 8 and 9, it will be understood that either an acceleration or a braking of the tow movement through the passageway may also be achieved with the use of radial slots or openings, such as 18, by the provision of a passageway the height of which varies from the tow inlet to the tow outlet of the passageway. In the arrangement of FIG. 8, where the inlet dimension a is smaller than the outlet dimension b, the air admitted into the passageway will have a tendency to flow more freely in the direction of the outlet, whereby the tow movement will be accelerated. In the arrangement of FIG. 9, where the inlet dimension a is larger than the outlet dimension b, the air admitted into the passageway will have a tendency to flow more freely in the direction of the inlet, whereby the tow movement will be opposed and thus retarded.

Although the banding jet construction so far described are characterized by the fact that the openings in the cylinder extend perpendicularly to the direction of movement of the tow through the passageway, i.e., the openings extend along respective generatrices of the cylinder (or of the convex surface presented by any other non-cylindrical body), it is also within the contemplation of the present invention that these openings may be otherwise oriented, and in particular obliquely relative to the direction of tow movement, i.e. along the lines of intersection between the convex surface of the cylinder and a plurality of vertical planes disposed at respective acute angles to the horizontal axis of the cylinder. In accordance with one aspect of this embodiment of the present invention, the cylinder 12b (see FIG. 6) is provided with a single set of openings 18b all of which are substantially parallel to one another and extend over a segment of the cylinder surface obliquely relative to the axis of the cylinder. In accordance with another aspect of this embodiment of the present invention, the cylinder (see FIG. 7) is provided with two sets of substantially parallel oblique openings or slots 18c and 18d, with the slots 18c being oriented transversely to the slots 18d. These two sets of slots thus are oblique to the direction of tow movement in opposite senses and are arranged in a herringbone pattern.

A particular advantage accruing from the use of a banding jet of the types represented by FIGS. 6 and 7 is that the air entering the passageway acts differentially on the various filaments of the tow and on various laterally adjacent groups or sub-bundles of filaments. As 'will be readily appreciated, even though any given increment of length of the tow entering and moving through the passageway in the jet will, prior to exiting from the latter, be directly impinged upon by air over its entire width, such action will neither commence nor terminate upon all of the filaments at the same time, since at no point of the jet is there any air-admitting opening or series of openings which extends entirely across the tow path. Thus, there will be a finite interval between the time one sub-bundle of filaments (which may in the limiting case consist of only one filament) is directly impinged upon by air and the time an adjacent sub-bundle of filaments is directly impinged upon by air. This interval greatly assists in the attainment of an enhanced efficiency of spreading of the filamentary strand. In view of the fact that the entire passageway is at all times filled with relatively 'turbulently moving air, it should be noted that the term directly impinged upon or any equivalent thereof is employed herein to designate only the condition existing when a given increment of length of the sub-bundle of filaments passes directly over an opening from which air is issuing.

As previously indicated, the air-admitting openings need not be exclusively located in the convex boundary surface, i.e. the cylindrical member, of the jet. Referring first to FIG. 10, it is seen that the banding jet 22 comprises an imperforate cylinder or like convexly surfaced member 23 partly about which extends a hollow shield 24 to the interior chamber 25 of which air or like fluid under pressure can be introduced via an inlet port 26. The shield is supported on and spaced from the member 23 by spacers 16 (as in the jets of FIGS. 1 to 9), and

the radially innermost wall 27 of the shield 24 is provided with air-admitting openings 28 through which the air from the plenum chamber 25 enters the passageway. In the embodiment of the invention illustrated in FIG. 11, the jet 29 comprises a hollow cylindrical or like convexly surfaced member 30 and a hollow shield 31 partly surrounding it and spaced therefrom by spacers 16. Both these members are provided within the bounds of the passageway defined t-herebetween with respective sets of air-admitting openings 32 and 33 to enable air introduced into the respective plenum chambers 34 and 35 through the ports 36 and 37 to enter the tow or filament passageway. The openings 32 and '33 are seen to be offset relative to one another. It will be readily apparent that the openings 28, 32 and 33 may, in terms of dimension, shape and/or orientation, be identical to any of the sets of openings 18 to 18d illustrated in FIGS. 2 and 4 to 7, and that the passageways between the members 23 and 30 and their respective shields or covers 24 and 31 may be of uniform height throughout or of variable height as indicated diagrammatically in FIGS. 8 and 9. As described above, the arcuate concavely surfaced shield 13, and the convexly surfaced member 12, may define a variable arc length of between about 75 and 180, as shown in FIGURE 12. Moreover, as shown in FIGURE 13, arcuate wedge-shaped spacer members may be employed.

In all of the various banding jets according to the present invention described hereinbefore, the air-admitting openings can be formed in any suitable manner. Merely by way of example, if elongated slots are employed, these may be formed by means of a double angle cutter mounted on a milling machine. Such a cutter could be employed to mill an angular groove from either the inside or the outside of the hollow member (cylinder or shield) until a 0.001 inch slit is broken through, after which the slot may be enlarged manually under periodic checking with a feeler gauge up to the desired dimension. This type of slot will, of course, have its walls angled one relative to the other, either symmetrically or asymmetrically with respect to its longitudinal center line. Alternatively, a slitting saw could be employed to form the slots, in which case the Walls of each slot will be parallel to one another.

The provision and use of arcuate banding jets according to the various embodiments of the present invention leads to a further advantage in the overall processing of filamentary material such as tow. In the systems presently in vogue and employing standard rectilinear or plane passageway banding jets, special bars, rails, rings or other guides, must be provided either at the inlet or at the outlet of the banding jet, and in many cases at both of these locations, to orient the filamentary material in the proper direction for banding and subsequent treatments. The banding jets according to the present invention, by virtue of the curvature of the passageway, inherently provide for a change in the direction of movement of the tow and thus are able to serve both the basic spreading function and the auxiliary guiding function. This obviates the heretofore unavoidable use of separate elements in the processing system for performing these functions. As a result, there are fewer parts to be replaced due to wear and tear, and concurrently the number of points at which snags in the overall processing operation could occur is materially reduced.

The banding jets employing a curved passageway ac cording to this invention are also found to operate in a superior manner with respect to plane passageway jets. Thus, the uniformity of spreading achieved is appreciably greater than in the standard jets, and the curved passageway banding jets function exceedingly well in removing false twist and longitudinal folds from tow as the latter is extracted from a bale.

The invention is further illustrated in the following example:

A banding jet with an arcuate filament passageway was constructed from a hollow aluminum cylinder 6 inches in outer diameter and a 120 cover or shield disposed concentrically with respect to the cylinder. The spacing between the inner concave surface of the shield and the outer convex surface of the cylinder, i.e., the height of the passageway, was 0.10 inch, and the width of the passageway Was 8 inches. The cylinder Was provided with 0.008 inch wide parallel slots which were milled into the cylinder from the outside with the aid of a 45 double angle cutter head the axis of cutting of which was oriented perpendicularly to the surface of the cylinder. The cover or shield was affixed to the cylinder in such a relative position that the slots were located between and from the entrance to the passageway. The jet was rigidly mounted 8 feet above a bale of 3.2 denier per filament50,000 total denier tow of cellulose acetate continuous filaments and in such a position that the passageway entrance was parallel to the floor. Air under a pressure of 2.25 p.s.i. was used, supplied by a 75 cubic feet per minute pump. The tension required to move this tow through the jet at uniform velocity was about 2 mgm. per filament or a total of about 30 gm. During a onehour run, no folds or false twists passed the jet, and the tow band width control was markedly superior to anything achieved with a standard flat banding jet.

When an arcuate air jet according to the present invention is employed in feeding fabrics or sheet materials, such as marquisettes, tricots, light-weight paper or plastic sheeting, or like materials of relatively little dimensional stability which would tend to be distorted or damaged by conventional feed rolls and tension-varying means, it is found that an air pressure of about 1 p.s.i. supplied by a pump having a delivery rate of about 25 cubic feet per minute yields very good results.

Although the preceding description of the jets according to the present invention and the processes involving their use has been primarily concerned with the utilization of compressible fluids, e.g., air or the like, it is contemplated by the present invention that incompressible fluids, e.g., liquids, may also be used in association with a treatment of the filamentary material while immersed in a liquid bath. The liquid applied to the material in the jet may be inert with respect to the composition of the filamentary material being treated, thus serving merely a feeding function (with or without accompanying acceleration or retardation), or it may be physically and/or chemically reactive relative to said material. In general, the openings in the jets employed in this manner will be somewhat larger than those in the air jets, although in any given case of either type the sizes of the openings will depend on the characteristics of the fluid being applied to the filamentary material as well as on the desired flow rates.

It is to be understood that the foregoing detailed de scription is given merely by way of illustration and that many variations may be made in the invention without departing from the spirit and scope thereof.

The embodiments of the invention in which :an exclusive property or privilege is claimed are defined as follows:

1. A banding jet, comprising a pair of members presenting, respectively, a convex surface and a concave surface, said members being juxtaposed to one another to define between said surfaces a shallow, relatively wide, arcuate passageway, at least one of said members being hollow and adapted to receive within the interior thereof a pressurized fluid, at least said one member being provided within the region of said surface thereof with a plurality of narrow openings disposed angularly relative to the arc length of said passageway and facilitating admission of said pressurized fluid into said passageway the arc length of said passageway being between about 75 and 2. A banding jet, comprising a pair of members present ng, e pectively, a convex surface and a concave surface, said members being juxt-aposed to one another and spacer means interposed between said members to space the concave surface from the convex surface so as to define between said surfaces a smoothly curved, shallow, relatively wide passageway, the convexly surfaced member being hollow and adapted to receive within its interior a pressurized fluid, said convexly surfaced member being provided within the region of said convex surface thereof with a plurality of narrow openings disposed angularly relative to the arc length of said passageway and facilitating admission of said pressurized fluid into said passageway.

3. A banding jet, comprising a pair of members presenting, respectively, a convex surface and a concave surface, said members being juxtaposed to one another and spacer means interposed between said members to space the concave surface from the convex surface so as to define between said surfaces a smoothly curved, shallow, relatively wide passageway, the concavely surfaced member being hollow and adapted to receive within its interior a pressurized fluid, said concavely surfaced member being provided within the region of said concave surface thereof with a plurality of narrow openings disposed angularly relative to the arc length of said passageway and facilitating admission of said pressurized fluid into said passageway.

4. A banding jet, comprising a pair of members presenting, respectively, a convex surface and a concave surface, said members being juxtaposed to one another to define between said surfaces a smoothly curved, shallow, relatively wide passageway, both said members being hollow and each being adapted to receive within its respective interior a pressurized fluid, the concavely surfaced member in the region of the concave surface thereof and the convexly surfaced member in the region of said convex surface thereof being provided with respective narrow openings offset with respect to each other and disposed angularly relative to the arc length of said passageway and facilitating admission of said pressurized fluid into said passageway.

5. A banding jet, comprising a hollow cylinder closed at its opposite ends, a curved shield juxtaposed to said cylinder and extending partly about the same, and spacer means interposed between said cylinder and said shield to space the concave surface of said shield from the convex surface of said cylinder so as to define between said shield and cylinder a smoothly curved shallow passageway, said cylinder being provided over a segmental portion of its periphery, the arc length of which is less than that of said shield, with a plurality of openings oriented angularly relative to the circumferential direction of said cylinder, the interior of said hollow cylinder being adapted to receive a pressurized fluid, and said openings facilitating admission of the pressurized fluid into said passageway.

6. A banding jet according to claim 5, the curvature of said concave surface of said shield being equal to that of said convex surface of said cylinder, and said spacer means comprising a pair of uniformly dimensioned arcu-ate bars, so that the radial height of said passageway is uniform from the inlet end to the outlet end thereof.

7. A banding jet according to claim 5, the curvature of said concave surface of said shield being equal to that of said convex surface of said cylinder, and said spacer means comprising a pair of Wedge-shaped arcuate bars so that the radial height of said passageway varies gradually from the inlet end to the outlet end thereof.

8. A banding jet according to claim 5, said openings in said segmental portion of said cylinder being formed to dire-ct the respective streams of the pressurized fluid, at the points of entry thereof into said passageway, radially of said cylinder.

9. A banding jet according to claim 5, said openings in said segmental portion of said cylinder being formed to direct the respective streams of the pressurized fluid, at

the points of entry thereof into said passageway, chordally of said cylinder.

10. A banding jet according to claim 5, said openings extending parallel to the axis of said cylinder.

11. A banding jet according to claim 5, at least some of said openings extending obliquely to the axis of said cylinder.

12. A banding jet according to claim 11, said openings being arranged in a herringbone pattern.

13. A banding jet according to claim 5, said openings being concentrated in that portion of said periphery of said cylinder which is coextensive with the initial section of said passageway.

14. A banding jet according to claim 5, said openings being concentrated in that portion of said periphery of said cylinder which is coextensive with the final section of said passageway.

15. A banding jet according to claim 5, said openings being substantially parallel to one another and extending perpendicularly to said path of movement of said strand through said passageway.

16. A banding jet according to claim 5, said openings being substantially parallel to one another and extending obliquely to said path of movement of said strand through said passageway.

17. A banding jet according to claim 5, said openings being arranged in two groups with the openings in each group being substantially parallel to one another, said openings in at least one of said groups extending obliquely to said path of movement of said strand through said passageway, and said openings in each group being oriented substantially transversely to the openings in the other group, thereby to define a herringbone pattern of said openings.

18. A banding jet, comprising a pair of members presenting, respectively, a convex surface and a concave surface, said members being juxtaposed to one another to define between said surfaces a smoothly curved, shallow, relatively wide passageway, the convexly surface-d member being hollow and adaptedto receive within its interior a pressurized fluid, said convexly surfaced member being provided within the region of said convex surface thereof with a plurality of narrow openings disposed angularly relative to the arc length of said passageway and facilitating admission of said pressurized fluid into said passageway, said convex surf-ace being of cylindrical curvature, and the arc length of said passageway being between about 75 and 19. The banding jet of claim 18, said openings in said convex surface extending along respective generatrices of said convex surface.

20. The banding jet of claim 18 at least some of said openings in said convex surface extending obliquely relative to the axis of curvature of said convex surface.

21. The banding jet of claim 18 said openings being arranged in a herringbone pattern.

References Cited by the Examiner UNITED STATES PATENTS 2,737,688 3/1956 Jackson 1966 2,908,045 10/1959 Steven-s 1966 2,968,982 1/ 1961 Cousino 226-97 X 3,017,309 l/l962 Crawford et al 1966 X 3,065,551 11/1962 Cohn et al 34--155 X 3,144,025 8/ 1964 Erlich.

3,167,408 l/1965 Justus et al 34-l60 X FOREIGN PATENTS 509,129 l/1955 Italy.

MERVIN STEIN, Primary Examiner.

DONALD W. PARKER, Examiner.

D. NEWTON, Assistant Examiner. 

1. A BANDING JET, COMPRISING A PAIR OF MEMBERS PRESENTING, RESPECTIVELY, A CONVEX SURFACE AND A CONCAVE SURFACE, SAID MEMBERS BEING JUXTAPOSED TO ONE ANOTHER TO DEFINE BETWEEN SAID SURFACES A SHALLOW, RELATIVELY WIDE, ARCUATE PASSAGEWAY, AT LEAST ONE OF SAID MEMBERS BEING HOLLOW AND ADAPTED TO RECEIVE WITHIN THE INTERIOR THEREOF A PRESSURIZED FLUID, AT LEAST SAID ONE MEMBER BEING PROVIDED WITHIN THE REGION OF SAID SURFACE THEREOF WITH A PLURALITY OF NARROW OPENINGS DISPOSED ANGULARLY RELATIVE TO THE ARC LENGTH OF SAID PASSAGEWAY AND FACILITATING ADMISSION OF SAID PRESSURIZED FLUID INTO SAID PASSAGEWAY THE ARC LENGTH OF SAID PASSAGEWAY BEING BETWEEN ABOUT 75 AND 180*. 